package network;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class TCPEchoServer {
    private ServerSocket serverSocket;
    public TCPEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }
    public void start() throws IOException {
        System.out.println("启动服务器");
        while(true) {
            Socket clientSocket=serverSocket.accept();
            Thread t1=new Thread(()-> {
                try {
                    processConnection(clientSocket);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }

            });
            t1.start();
        }
    }

    // 针对一个连接,提供处理逻辑
    private void processConnection(Socket clientSocket) throws IOException {
        // 先打印一下客户端的信息,IP和端口号
        System.out.printf("[%s:%d] 客户端上线!\n",clientSocket.getInetAddress(),clientSocket.getPort());
        //获取到socket中持有的对象
        try(InputStream inputStream=clientSocket.getInputStream();
            OutputStream outputStream=clientSocket.getOutputStream()) {
            // 使用Scanner包装一下inputStream,就可以更方便地读取这里的内容了
            Scanner scanner=new Scanner(inputStream);
            PrintWriter printWriter=new PrintWriter(outputStream);
            while(true) {
                // 1. 读取请求并解析
                if(!scanner.hasNext()) {    //scanner无法读取出数据,说明客户端已经关闭了连接
                    break;
                }
                String request=scanner.next();
                // 2. 针对请求计算响应
                String response=process(request);
                // 3. 把响应写回给客户端
                // 此处可以按照字节数组来写,也可以使用PrintWriter
                //outputStream.write(response.getBytes());
                printWriter.println(response);
                printWriter.flush();
                // 4. 打印日志
                System.out.printf("[%s:%d] req=%s;resp=%s\n",clientSocket.getInetAddress(),clientSocket.getPort(),request,response);
            }
        }catch(IOException e){
            e.printStackTrace();
        } finally {
            System.out.printf("[%s:%d] 客户端下线!\n",clientSocket.getInetAddress(),clientSocket.getPort());
            clientSocket.close();
        }
    }
    private String process(String request) {
        return  request;
    }

    public static void main(String[] args) throws IOException {
        TCPEchoServer server=new TCPEchoServer(9090);
        server.start();
    }
}
